Heat the coconut oil in a large high-sided skillet or wok over high heat. Add the beef and pineapple and season with a small pinch of salt and black pepper, if desired.
Stir-fry the beef and pineapple over high heat until the beef is cooked through and the pineapple develops a slight golden color, approximately 2-3 minutes.
Add the tamari or coconut aminos and stir-fry for another 1-2 minutes, or just until the mixture is warm and bubbly.Taste and season with additional salt and black pepper, if desired.
Remove from heat and stir in the scallions. Transfer to individual plates and serve immediately. Enjoy!